1. Field of the Invention
The present invention relates to an optical film, a polarizing plate using the same, and a liquid crystal display device.
2. Description of the Related Art
Optical films such as a cellulose acylate film are used in a variety of liquid crystal display devices as optical members for the liquid crystal display devices, for example, a support for an optical compensation film, a protective film for a polarizing plate, or the like.
Occasions are increasing for liquid crystal display devices to be used outdoors as mainly portable devices, other than to be used indoors as TVs and the like. Therefore, there is a demand for the development of liquid crystal display devices capable of withstanding applications under a higher temperature and a higher humidity than in the related art.
Furthermore, there is an intensifying demand for liquid crystal display devices to withstand harsh operation conditions in diversifying applications and a higher level of durability than in the related art has been demanded every year.
Regarding optical films for which a cellulose acylate film is used, it is known that, in order to further improve the performance or solve a variety of problems in relation to the characteristics or manufacturing of the optical films, a specific compound is added to the film.
For example, a gelatinizing agent having a specific structure with an intention of gelatinizing a cellulose acylate solution in a solvent cast method (refer to JP2002-322294A), an organic acid exhibiting a specific acid dissociation constant with an intention of improving the durability of a polarizer that deteriorates at a high temperature depending on a variety of humidity conditions (high humidity or low humidity) (refer to JP2011-118135A), barbituric acid having a specific substituent at the fifth position with an intention of suppressing the change in optical characteristics that change depending on humidity (refer to JP2011-126968A), and the like have been proposed.